1. Field of the Invention
The present invention relates to a photomultiplier or an electron multiplier having dynode arrays for multiplying electrons by the secondary electron emission effect and, more particularly, to a so-called linear multi-anode photomultiplier and electron multiplier in which portions thereof, on which a plurality of light beams to be measured or energy beams of electrons, ions and so forth are incident, are aligned one-dimensionally.
2. Related Background Art
FIGS. 1, 2 and 3 show an example of a conventional linear multi-anode photomultiplier. This photomultiplier is a head-on type photomultiplier in which incident window 2 for receiving light beams to be measured are formed on one end face of a glass bulb 1. Transmission type photoelectric surfaces 3 for converting the incident light to be measured to photoelectrons are formed on the inner surface of the incident window 2 in a one-dimensional array. One focusing electrode 4 is arranged inside the glass bulb 1 to be parallel to the incident window 2, and openings 5 are formed in a one-dimensional array at a portion of the focusing electrode 4 opposing the photoelectric surfaces 3. When a plurality of light beams to be measured are incident on the respective photoelectric surfaces 3 to generate photoelectrons, the photoelectrons are guided to corresponding dynode arrays 6 through the openings 5. The dynode arrays 6 of the photomultiplier shown in FIG. 1 have in-line dynode structure. The photoelectrons are multiplied by the secondary electron emission effect in each stage of dynode 7 of the respective dynode arrays 6, and the multiplied photoelectrons are finally captured by anodes 8 as output signals.
In the conventional photomultiplier described above, some of leaking electrons from the gaps among the dynodes 7 of each dynode array 6 enter the gaps among the dynodes 7 of an adjacent dynode array 6 to cause so-called crosstalk. Crosstalk impairs independency of each dynode array 6 and degrades the detection precision of the light beams to be measured.
The photomultiplier described above is a transmission type photomultiplier having photoelectric surfaces on the inner surface of the incident window. A reflection type photomultiplier has a similar problem of crosstalk.
An electron multiplier for detecting the energy beams of electrons, ions and so force also has a problem of crosstalk since its dynode array has a substantially same arrangement.